Approximately 15% of patients recover from hepatitis C virus (HCV) infection while 85% become persistently infected, resulting in various degrees of associated chronic liver disease. In this study comparisons will be made among patients who rapidly recover, those who have delayed recovery, those with persistent infection and stable chronic disease, and those with rapidly progressive, fatal infection. The parameters measured will be viral burden (initially and over time), HCV genotype, the number of viral quasi-species (extent of viral heterogeneity) at the time of infection and subsequently, neutralizing antibody responses and, if appropriate technology is available, cytotoxic T cell responses. The goal is to determine if any of these parameters can predict outcome and hence serve as adjuncts to therapeutic decisions, particularly decisions regarding early intervention.